An iron bar weighing 56.0 g reacts completely with excess hydrochloric acid according to the equation: Fe + 2HCl → FeCl2 + H2. What mass of H2 is produced?

• A. 2.0 g
• B. 2.0 g
• C. 1.0 g
• D. 1.0 g

Answer: (A)

Verified step by step guidance

1. Write down the balanced chemical equation: \(\mathrm{Fe} + 2\mathrm{HCl} \rightarrow \mathrm{FeCl}_2 + \mathrm{H}_2\).
2. Calculate the number of moles of iron (Fe) using its given mass and molar mass: \(\text{moles Fe} = \frac{\text{mass Fe}}{\text{molar mass Fe}} = \frac{56.0\,\mathrm{g}}{55.85\,\mathrm{g/mol}}\).
3. Use the mole ratio from the balanced equation to find the moles of hydrogen gas (\(\mathrm{H}_2\)) produced. According to the equation, 1 mole of Fe produces 1 mole of \(\mathrm{H}_2\), so \(\text{moles } \mathrm{H}_2 = \text{moles Fe}\).
4. Calculate the mass of hydrogen gas produced by multiplying the moles of \(\mathrm{H}_2\) by its molar mass: \(\text{mass } \mathrm{H}_2 = \text{moles } \mathrm{H}_2 \times 2.02\,\mathrm{g/mol}\).
5. The result from step 4 gives the mass of \(\mathrm{H}_2\) produced when 56.0 g of iron reacts completely with excess hydrochloric acid.